1. Field of the Invention
The present invention relates to an image forming apparatus such as a laser printer.
2. Description of the Related Art
An image forming apparatus such as a laser printer has a photoconductor drum, a transfer roller, a heating roller and a pressure roller. The photoconductor drum and the transfer roller are disposed to face each other. The heating roller and the pressure roller are disposed on the downstream side of the photoconductor drum and the transfer roller in the paper conveyance direction so as to face each other. A toner image based on image data is carried on the photoconductor drum. Due to application of transfer bias to the transfer roller, the toner image carried on the photoconductor drum is transferred onto a sheet of paper passing between the photoconductor drum and the transfer roller. After that, the sheet of paper having the toner image transferred thereto passes between the heating roller and the pressure roller. In this event, the sheet of paper is heated by the heating roller and pressed by the pressure roller. Thus, the toner image is fixed onto the sheet of paper so that the formation of an image on the sheet of paper is attained.
In the image forming apparatus configured thus, a gear for rotating the photoconductor drum and the heating roller is provided in an axial end portion of the photoconductor drum or the heating roller so as to rotate integrally with the photoconductor drum or the heating roller due to a driving force input to the gear. To this end, the gear is attached to the photoconductor drum or the heating roller so as to be disabled from rotating relatively thereto.
For example, the following configuration has been known. That is, in the photoconductor drum, a gear is fitted to an end portion of a cylinder made of an aluminum pipe. The end portion of the cylinder is bent inward so as to have a crease in a direction (circumferential direction) perpendicular to the axial direction of the cylinder, so as to engage with a concave portion formed in the outer circumference of the gear. Thus, the gear is attached to the cylinder so as to be disabled from rotating relatively thereto (for example, see JP-A-6-250576).